Coenzyme A, pyridoxal phosphate and NAD labeled with isotope in the beta-alanine, pyridine ring and niacinamide moieties respectively, will be presented both intralumenally and in the perfusate to perfused rat intestine to determine the rate of release of pantothenate, pyridoxal and niacin during digestion. The rates of absorption of isotope into the intestinal tissue and the perfusate, and identification of the labeled compounds will be evaluated. When the behavior of each compound is characterized in this tissue, perfusion experiments will be extended to liver, kidney and striated muscle to determine their capacity to take up the vitamins and their coenzymes from the perfusate and their capacity to synthesize and degrade these coenzymes. The results will be extended to isolated cells (erythrocytes, lymphocytes, hepatocytes, and mucosal cells) and to surgically modified rats, when needed, to provide an understanding of the role of each tissue in handling these vitamins and their cofactors. Well established methods employing high voltage paper electrophoresis, column chromatography and paper chromatography will be used to identify and quantitate the labeled intermediates. Emphasis will be placed on the mechanism of transport of these vitamins, their coenzymes and related metabolites by animal cells.